Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

2
Refrigerants
Flammability
Several of the blends use flammable refrigerants as one of the
components, and some blends just use a mixture of hydrocarbons.
Therefore, some safety concerns are raised for their application.
Some regions and countries set a limitation in specific equipment
for such kinds of blends or even forbid their use. In developed
countries, the HCFC based blends for replacement of R12 were not
widely used for the manufacturing of new equipment or retrofitting
of existing equipment partly due to its ODP value, flammability and
servicing complications. Also, the retrofitting of appliances is not
practiced in developed countries mainly because of the availability
of recycled CFC for servicing and high retrofitting cost due to higher
labour charges compared to new equipment cost.
Pros and Cons of refrigerant blends
Pros of refrigerant blends:
• The refrigerant blends provide another way to assist the country in
complying with the CFCs phase-out provision under the Montreal
Protocol whilst not harming the interests of the end users.
• The refrigerant blends (if the main components are either R22/
R152a/HCs) can be cheaper than R134a and other alternatives;
they tend to be widely available.
• The HCFC based refrigerant blends as mentioned above aimed
to replace R12 can mostly be used with mineral oils and can
provide acceptable performance in retrofitted equipment.
Cons of refrigerant blends:
• HCFC-based blends are an interim CFC replacement solution.
• Due to the non-azeotropic and possible flammable characteristics,
the servicing procedure especially charging would be complicated
and the technicians should be informed to follow proper handling
procedures.
• It is more difficult to estimate the amount of superheat and subcooling
when commissioning or servicing a system.
• Leakage from heat exchangers and subsequent re-filling will
lead to a gradual change in composition, thereby resulting in a
change in performance and operating characteristics over time.
• The introduction of more refrigerants in the market might
confuse the technicians, causing more cases of crosscontamination
in running the refrigeration system.
• Even though the short-term impact on the performance of the
equipment might not be noticed by the equipment owner, it is
believed the cross-contamination of a refrigerant/lubricant will
reduce the equipment’s energy efficiency and its performance,
and shorten the operational life of the equipment.
• More blends will also complicate the recovery/recycling
programme due to the cross-contamination, as equipment with
the blends might not be properly labelled or the technicians may
just ignore the label.
• Some blends are advertised to replace R134a, so it might cause
backward retrofitting from R134a to HCFC-based blends.
50